FWIW, most shotgun mics are based around a supercardioid capsule, and exhibit standard supercardioid directivity at frequencies below the range where the interference tube becomes effective. What made the gargantuan EV 643 remarkable other than it's monstrous size was that it retained the tighter front-lobe shotgun pattern down to ~700Hz before the standard supercard directivity took over below that. The tiny DPA 4098 interference tubes which are only a couple inches long would probably only make the omnidirectional 4060/61 capsule directional above something like 10Khz or more (guessing), and is probably intended to fine tuning the directivity pattern of just the topmost octaves.
The other method of achieving greater than first-order directivity is via DSP - combining and manipulating the signals from more than one capsule, which is how the Schoeps SuperCMIT achieves such radical directivity with minimal artifacts using a relatively short interference tube. They start with a supercardioid, made more directional at high frequences via the interference tube in the standard shotgun way, but also more directional at lower frequencies than where the tube is effective via DSP manipulation with a second rear-facing capsule located a few inches behind the primary capsule.
Otherwise, any shotgun directivity beyond that of the native polar pattern of the capsule is largely determined by the length of the tube.